Upon attaining revered with The Oracles faction in Sholazar Basin, players can purchase a [Mysterious Egg]. Because it's unique, only one egg can be "incubated" at a time. After three days, the egg becomes lootable as a [Cracked Egg]. Possible loot includes [Aged Yolk], a Green Proto-Drake mount, or one of four vanity pets:

Among snakes, the cobra hatchling is currently unique in its looks. I don't know whether Blizzard intends to add any more pets with this model in the future, but meanwhile this one will be my snake of choice to level up.